<template>
    <div class='header'>
        <router-link 
        tag='div' 
        to='/' 
        class='header-abs'
        v-show="showAbs">
            <div class="iconfont header-abs-back">&#xec45;</div>
        </router-link>
        <div 
        class='header-fixed'
        v-show="!showAbs"
        :style="opacityStyle">
            <router-link tag='div' to='/' >
                <div class="iconfont header-fixed-back">&#xec45;</div>
            </router-link>
            景点详情
        </div>
        
    </div>
</template>

<script>

export default{
    name:'DetailHeader',
    data (){
        return {
            showAbs:true,
            opacityStyle:0
        }
    },
    activated (){
        window.addEventListener('scroll',this.handleScroll)
    },
    deactivated (){
        window.removeEventListener('scroll',this.handleScroll)
    },
    methods:{
        handleScroll (){
            
            const top = document.documentElement.scrollTop
            if(top>60 ){
                this.showAbs = false
                let opacity = top/140
                opacity = opacity > 1? 1 : opacity
                this.opacityStyle = {
                    opacity
                }
            }else{
                this.showAbs = true
            }
        }
    }
}
</script>

<style lang="stylus" scoped>
@import '~styles/varibles.styl';
.header
   
    .header-abs
        position absolute
        left .2rem
        top .2rem 
        width .8rem
        height .8rem
        border-radius .4rem
        background rgba(0,0,0,.8)
        text-align center
        line-height .8rem
        z-index 2
        .header-abs-back
            color #fff
            font-size .4rem
    
    
    .header-fixed
        z-index 2
        position fixed
        overflow :hidden
        top 0 
        left 0 
        right 0
        height $headerHeight
        line-height $headerHeight
        text-align center
        color #fff
        background $bgColor
        font-size .32rem
        .header-fixed-back   
            width .64rem
            text-align center
            font-size .4rem
            position absolute
            top 0
            left 0
            color #fff    
</style>
